The Gordon Research conference on "Oxygen Radicals in Biology" is designed to provide chemists, biologists, biochemists, cell biologists, clinicians, and other biomedical scientists with state of the art knowledge on reactive oxygen species and their interactions with other radicals, including nitric oxide, in chemical and biological systems. This research conference is held every two years; the next meeting will be held February 5-10, 2006 at the Ventura Beach Marriot Hotel, Ventura, California. Thirteen conferences have been held since 1981 and they have proven to be extremely productive based on the large number of applicants and the post-meeting evaluations. Funds are requested to partially support travel subsistence and registration costs for speakers from the United States and abroad and productive graduate students/postdoctoral candidates. The speakers listed in this program were selected based on the suggestions from the previous chairs, co-chairs and attendees at the past conference. Speakers have been invited to present their latest research on oxygen radicals in biology. Sessions will include: oxidants and antioxidants in infection and inflammation, emerging technologies and biomarkers in free radical biology; and several sessions on signal transduction involving NADPH oxidases, thiol oxidation, lipid derived radicals and nitric oxide. The invited speakers represent current and future leaders in free radical research in pulmonary, cardiovascular and diseases and inflammation and in toxicology. In addition, Professor Christine Winterboura will present a Plenary Lecture entitled: "Understanding oxidative stress: From the chemistry of superoxide to the lungs of babies." Two separate poster sessions of two days each are scheduled for an anticipated 50-70 posters. Total attendance is limited to 135 by Gordon Conference rules. The Gordon Conference provides an excellent and needed forum for the diversity of both participants and research areas. The main strength of this Gordon Research Conference is the opportunities offered for scientists in different disciplines to interact in an extended and uninterrupted fashion. This type of interaction generally results in new collaborative research initiatives. The Gordon Research Conference on Oxygen Radicals in Biology plays a crucial role in exploring frontier research in this important and clinically-relevant field.